This invention relates to a continuous electrolytic treatment of circulating washings in plating processes and apparatus therefor.
In general, plated articles are subjected to washing treatment with water. When more economical utilization of water is intended, a plating solution is gradually accumulated in a washing vessel placed adjacent to a plating bath, resulting in a considerable increase of concentration of the plating solution in this washing. As the concentration increases, the plated metal dissolves into the washings of the washing vessel, entailing a deteriorated quality of the plated article. The discharge of such concentrated washings is not be permitted to avoid development of undesired public nuisance.
In order to overcome the foregoing disadvantages, batch processes have been widely employed, which require the addition of a a considerable amount of a treating agent at much additional cost.
After extensive studies, it has been found that a metallic component may be conveniently collected by arranging an electrolytic cell in communication with the washing vessel disposed in abutting relation with a plating bath and providing the cell with a filtering means for the collection of metal, thereby to precipitate the metallic component out of the washings by electrolysis coupled with subsequent filtering. Further, it has also been found that this treatment holds a predetermined concentration of the plating solution in the washings, having an excellent quality of the plated article and at a relatively low cost.
Still further, it has been found that the metallic component may more conveniently be recovered by providing a movable scraper on the cathode of the electrolytic cell for removal and collection of the metals deposited thereon. By periodically operating the scraper, the resulting precipitates can be filtered by a convenient filter connected to the bottom of the electrolytic cell.